春玉米产量、氮素利用及矿质氮平衡对施氮的响应

通过在辽宁省昌图县的田间试验,研究了不同施氮水平(0、60、120、180、240和300 kg hm-2)对春玉米产量、氮素利用及农田矿质氮平衡的影响。结果表明:春玉米产量随施氮量增加而显著提高,当施氮量高于N 240 kg hm-2时,产量有减少趋势;氮素当季利用率随施氮量增加先增加后降低,在施氮量180 kg hm-2时达到最大,为27.95%。随着施氮量增加,氮肥农学利用率、氮素吸收效率和氮素偏生产力均显著降低,而氮肥生理利用率和氮肥表观残留率均先增加后降低,这与氮肥表观损失率的变化正好相反。作物吸氮量随施氮量增加而显著增加,氮盈余主要以土壤残留为主,表观损失在氮盈余中的比例虽小,但随着施氮量增加而明显增加。低量施氮(<180 kg hm-2)主要引起土壤矿质氮残留量的显著增加,而高量施氮(240 kg hm-2和300 kg hm-2)主要引起土壤氮素表观损失量的显著增加。在本试验条件下,合理施氮量应控制在180～209 kg hm-2左右。

Response of spring maize to nitrogen application in grain yield, nitrogen utilization and mineral nitrogen balance

A field experiment,designed to have 6 levels of nitrogen application rates(0,60,120,180,240 and 300 kg hm-2),was conducted at Changtu county of Liaoninng province to investigate effects of nitrogen application on spring maize in yield,nitrogen utilization and maize field mineral nitrogen(Nmin) balance.Results show that the yield of spring maize increased significantly with increasing nitrogen application rate,but once the rate exceeded 240 kg N hm-2,yield of the crop began to show a declining trend.In the current season,N recovery rate(NRR) increased first and then decreased with increasing N application rate,and reached the highest,27.95%,when 180 kg N hm-2 was applied.With the nitrogen application rate further rising on agronomic N use efficiency(ANUE),nitrogen uptake efficiency(NUE) and nitrogen partial productivity(NPP) all decreased significantly,however,physiological N use efficiency(PNUE) and nitrogen apparent residual rate(NARR) both first increased and then decreased,which is just contrary to the changes in nitrogen apparent loss rate(NALR).The crop nitrogen uptake increased significantly with increasing nitrogen application rate,and surplus nitrogen remained in the soil mainly in residue form.Though apparent nitrogen loss accounted only for a small proportion of the nitrogen surplus,its increase with increasing nitrogen application rate was significant.Low nitrogen application rate(<180 kg hm-2) mainly induced significant increase in soil residual Nmin,while high nitrogen application rate(240 kg hm-2 and 300 kg hm-2) did in nitrogen apparent loss.Under the experimental conditions,a reasonable nitrogen application rate should be controlled at about N 180~209 kg hm-2.